1. Field of the Invention
This invention relates to an improved control system and control device for controlling the output temperature of a heating means as well as to methods of operating such a system and making such a control device.
2. Prior Art Statement
It is known to provide a control system for a heating means that has control means for comparing a variable electrical signal that has a value in relation to the output temperature of the heating means and a selected electrical signal that has a value in relation to a selected temperature setting to control the operation of a heating means to tend to produce an output temperature substantially equal to the selected temperature.
It is also known to provide a control device having a temperature sensing unit for providing motion of a part thereof in relation to the temperature being sensed by the unit, the device having electrical switch means operatively interconnected to the part to be operated thereby when the part is in a certain position thereof relative to the control device.
For example, see the U.S. Patent to Hild et al, U.S. Pat. No. 3,419,707, wherein such a known control device has a rod and tube temperature sensing unit for providing linear motion of the part thereof in relation to the temperature being sensed by the unit, the movable part thereof operating electrical switch means.
It is also known to provide a bellows operated rheostat or potentiometer wherein the wiper arm of the rheostat is pivotally positioned relative to the coil means of the rheostat by a bellows operated temperature sensing means. For example, see the U.S. Patent to Middleton et al, U.S. Pat. No. 2,423,609.